What major characteristic do we get of the first boy?

We immediately know that the first boy, Ralph, doesn't wait around to see what will happen next. He's up, moving, and perusing his surroundings. He's ready to take charge.

The boy with fair hair lowered himself down the last few feet of rock and began to pick his way toward the lagoon. Though he had taken off his school sweater and trailed it now from one hand, his grey shirt stuck to him and his hair was plastered to his forehead. All round him the long scar smashed into the jungle was a bath of heat. He was clambering heavily among the creepers and broken trunks when a bird, a vision of red and yellow, flashed upwards with a witch-like cry; and this cry was echoed by another.